Carton blank



FIG. 1 is a top plan view of a carton blank showing my new design;

FIG. 2 is a right side elevational view thereof; the left side elevational view being a mirror image thereof;

FIG. 3 is a rear elevational view thereof; and,

FIG. 4 is a front elevational view thereof. 

The ornamental design for a carton blank, as shown and described. 